CENTENNIAL, Colo. — Governor John Hickenlooper on Sunday credited security procedures adopted after the 1999 massacre at nearby Columbine High School for helping to put a quick end to last week’s shooting at Arapahoe High School.
Hickenlooper asked the nation for prayers for Claire Davis, the 17-year-old girl who was critically wounded by a classmate at the suburban Denver high school.
Police said Karl Pierson, an 18-year-old student, shot Davis at close range before killing himself. Davis is hospitalized at Littleton Adventist Hospital, where she remained in a coma Sunday.
“Her parents are two of the most wonderful people you could ever hope to meet,’’ Hickenlooper said on CBS’s “Face the Nation.’’ “I just can’t imagine what they are going through. It’s unspeakable.’’
About 500 classmates held a candlelight vigil Saturday for Davis, who was sitting with a friend near the school library when she was shot in the head.
Arapahoe County Sheriff Grayson Robinson has said investigators think she was shot at random by Pierson, who had gone into the school looking for a teacher with whom he had a dispute.
Pierson may have been nursing a grudge against the teacher — a librarian and head of the school debate team — since September. Pierson was on the team and had been disciplined by the librarian for reasons yet to be disclosed, the sheriff said.
He said Pierson threatened that teacher in September and came to the school Friday intending to harm him and inflict numerous other casualties.
Pierson excelled at speech and debate and was passionate about the team, friends said. They described him as a smart student who apparently did not shirk from confrontations in class.
‘‘He’s a funny kid. He’s smart. He’s in the Eagle Scouts, a very intelligent kid. Did not like being wrong,’’ said August Clary, who was a friend of Pierson. ‘‘If you’re arguing with him, it’s going to be — that’s a feat if you win an argument against him.’’
‘‘He would not be afraid to tell someone how he feels,’’ said Zach Runberg, 18, a senior in Pierson’s English class.
Pierson legally bought a shotgun on Dec. 6 at a local store, and he purchased ammunition the morning of the shootings. He managed to ignite a Molotov cocktail inside the school library before he killed himself, as a fast-acting school security officer, a deputy sheriff, closed in, Robinson said.
That officer’s aggressive response prevented more casualties, Robinson said. It is a tactic adopted nationwide after Columbine, in which first responders cordoned off the school before pursuing two student gunmen inside. The two killed 12 students and a teacher before killing themselves.
‘‘It’s nice to see how well the system worked. It’s a remarkable improvement from before. This could have been much, much worse,’’ Hickenlooper said.
After the Aurora, Colo., theater shootings and the Newtown, Conn., school shootings, Colorado’s Democrat-led legislature this year implemented gun control measures that limited the size of ammunition magazines and instituted universal background checks.
Colorado also appropriated more than $20 million for mental health hot lines and local crisis centers.
The measures were intended to address violence associated with so-called assault rifles, not shotguns that are widely owned for hunting and sport.
Hickenlooper acknowledged that the latest shooting raised again questions about guns and violence. But he noted that Pierson ‘‘didn’t seem to exhibit any signs of mental illness,’’ and he cautioned that the investigation was in its early stages.
‘‘Everyone in Colorado is asking the same questions,’’ the governor said. ‘‘On the one hand there is a deeply held conviction for the freedoms laid out in the Second Amendment, but also a very, very strong conviction about the safety of children and the safety of the community.’’
Friday’s shooting, he said, ‘‘defies any explanation, and you know we are searching for some pattern.’’
Police said Pierson fired six shots from a pump-action shotgun between the moment he walked into Arapahoe High School and the moment he killed himself in a library. The attack lasted just 80 seconds.
Anyone 18 and older is allowed to buy a shotgun in Colorado; only those over 21 can legally buy a handgun.
In his weekly radio address last week, President Obama said the nation has not done enough to make its communities safer by keeping dangerous people from getting guns and healing troubled minds. Gun restrictions backed by the president in response to the shooting faced stiff opposition and ultimately stalled in the Democrat-controlled Senate.
‘‘We have to do more to keep dangerous people from getting their hands on a gun so easily. We have to do more to heal troubled minds. We have to do everything we can to protect our children from harm and make them feel loved, and valued, and cared for,’’ Obama said.
Observances to mark the one-year anniversary of the school shooting in Newtown, Conn., were held around the country Saturday.
The bells rang 26 times at St. Rose of Lima church in Newtown beginning at 9:30 a.m. — the moment the gunman shot his way into the school on Dec. 14, 2012 — and names of the victims were read over a loudspeaker.
About 100 people gathered in Tucson as former representative Gabrielle Giffords and her husband planted a yellow rose bush in a memorial garden created after the 2011 shooting there that nearly killed her. Giffords’s husband, Mark Kelly, said it was important to pause and support families of the Newtown victims.
In Denver, a day after the attack at Arapahoe High School, more than 200 people gathered to sing and offer prayers for the Newtown victims and families.